Gas lift retrievable valve



Sept. 13, 1960 Filed Nov. 14, 1957 J. A. BLUM GAS LIFT RETRIEVABLE VALVE2 Sheets-Sheet 1 (/U/lUJ A. B/um INVENTOR.

ATTORNEY Sept. 13, 1960 L/U/lUJ /l. B/um INVENTOR.

BY \POQ AK. A.w\;m

ATTORNEY United States Patent GAS LIFT RETRIEVABLE VALVE Julius A Blum,Caracas, Venezuela (2444 S. York, Denver 10, C010.)

Filed Nov. 14, 1957, Ser. No. 696,453 '3 Claims. (Cl. 137-155) Mypresent invention relates to a gas lift valve of the type adapted forartificial production of subsurface oil from a well by a method whichinvolves lifting the oil to the surface by gas pressure. It isparticularly intended to provide a valve that may be inserted andremoved quickly without the expensive operations that normally arenecessary for such installation. This application is acontinuation-in-part of my co -pending application Serial No. 342,121,filed March 13, 1953, now abandoned.

In the afield of oil production, wells are identified as flowing wells,those Which'flow or gush because of the pressure of gas present therein,or non-flowing wells, those in which the natural gas pressure has becomeexhausted or reduced to a point where it is insufiicient to lift theliquid to the well head. Various types of artificial productiontechniques have been developed for use in producing oil from non-flowingwells, one of the more recent of which involves introducing gas underpressure into the annular space between the'internal tubing whichcontains the liquid and the casing which defines the well, and allowingsuch gas to enter the tubing at a desired intermediate point to lift theliquid above such point to the surface. Gas lift valves are necessary toregulate the introduction of gas into the tubing, and the presentinvention is a novel and improved device of this type.

Certain shortcomings of conventional gas lift valves have becomeapparent. Many of these units have proved to be wasteful of gas, forthey allow gas flow to continue beyond the time when there is sufficientliquid present in the tubing to justify its use. Further, in placingsuch valves, the tubing must be lifted from the well, the valves placedin the proper location and the tubing replaced, an expensive andoftentimes inconvenient series of operations. H

My invention overcomes these objectionable features by providing a valvewhich is slidable within the tubing. 'A perforation may be made at thedesired point in the tubing by well-known surface operated means, or apreviously existing opening may be used. My valve includes spacedpacking elements which provide seals at each side of the aperture whenthe unit is positioned generally within the proper area- Gas from thespace between the casing and the tubing enters through the perforationand fills the space between the packings from whence it is communicatedto a valve operating member which moves in response to various pressuresto admit only as much gas to the tubing asis necessary to lift the wellliquids upwardly toward the surface. 7

. Accordingly, it is an object of my invention to provide an improvedgas lift valve.

M It is a further object of my invention to provide a gas lift valvewhich may be placed or retrieved from the surface without removing thetubing.

It is a further object of my invention to provide a gas lift valve whichmay be operatively positioned with only general attention to alignmentwith a preexisting opening in'th'e tubing.

It is a further object of my invent-ion to provide a gas lift valvehaving pressure responsive means whereby the most economical use of thelifting gas is made possible.

Other objects and advantages of my invention will be made apparent inthe following detailed description studied in conjunction with theaccompanying drawings in which:

Fig. 1 is a sectional elevation of a typical producing well with my gaslift valve in place;

Fig. 2 is an enlarged elevation of the central portion of my valve,partly in section, taken substantially on the plane indicated by line 22of Fig. 1;

Fig. 3 is a cross-section taken substantially on the plane indicated bythe line 3-3 of Fig. 2;

Fig. 4 is a cross-section taken substantially on the plane indicated bythe line 4-4 of Fig. 2; and

Fig. 5 is a cross-section taken substantially, on the plane indicated bythe line 55 of Fig.

In the installation view of my invention shown in Fig. 1, a well casing1 extends downwardly in a hole drilled into the earth 2. Tubing 3 islocated Within the casing 1 in spaced relation thereto, and the casinghead 4 seals the tubing 3 in gas-tight relation to the casing 1. Adischarge conduit 5 is connected through the casing head 4 to the tubing3 for delivery of oil and other fluid there from. A gas conduit 6 isconnected through the casing head 4 into the annular space 7 between thecasing 1 and tubing 3 to introduce therein gas pressure from a suitablesource not shown.

The valve unit housing 10 is a composite hollow body, preferably tubularin shape and of such size that it readily slides within the tubing 3. Itcomprises a lower portion 11, a central portion 12, and an upper portion13, all of which define an internal conduit 14. The lower portion 11 isclosed at the bottomand has a plurality of lateral perforations 15through the walls thereof so that fluid in the well below the unit mayenter the internal conduit 14. A packer or sealing ring 16 is providedabout the lower portion 11 above the perforations 15 for contact withthe internal walls of the tubing 3. This member preferably is reinforcedby a second seal-ing ring '17. These sealing rings are of neoprene orother oil resisting rubber to provide a packer or sealer so that oil orgas may not pass thereby. The central portion 12 contains the workingvalve which is spaced therein so as not to block ilow upward through theinternal conduit 14. The upper portion 13 has an open upper end 18 whichallows fluid to re-enter the tubing 3 above the unit housing. Thus theconduit 14 provides a channel of flow from the lower perforations 15 tothe upper end 18 while the working valve within the central portion 12controls the introduction of gas, as will be explained. A second set ofsealing rings 19 and 20 is carried about upper portion 13' to functionin a manner similar to the lower sealing rings 16 and 17 and provide asealed annular chamber 21 between the tubing 3 and the housing 10.

The tubing 3 is provided with one or more lateral ports 22 so that gasunder pressure may be communicated from the annular space 7 between thetubing 3 and the casing 1 and into the sealed chamber 21 between thepackers '16 and 17, and 119 and 20. The distance between the packingrings provides a margin for error in vertical alignment of the unitwithin which the aperture 22 may be situated without affecting theoperability of the unit Referring now to Figs. 2 through 5, the workingvalve of the 'unit which is carried within the conduit 14 in the centralportion 12 of housing 10 comprises a composite hollow tubular body 23which is closed at each end. This body is spaced within the housing 10by external lugs .24 near the top, and external lugs 25 near the bottom.

At an intermediate point along its length are lugs 26 which areinternally threaded to receive the attaching bushings 27. Each of thebushings is threadably secured through the walls of the housing to thelugs 26 and is hollow to establish communication between the sealedchamber 21 and the main valve chamber 28 within the body 23. Appropriatecheck valve means 29 are provided to insure that excessive back pressurein chamber 28 is not communicated to chamber 21. Conventional O-ringseals 30 are included between the bushings 27 and their seats in thehousing 10. Thus, passages or ports and spaces 6, 7, 22, and 27 form, ineffect, a continuous conduit for supplying compressed gas to chamber 28in the valve body.

The main valve chamber 28 is closed at its top by valve seat member 32which is positioned within the tubular body 23 by any suitable meanssuch as the screw threads 33. A longitudinal conduit 34 extendstherethrough into communication with upper valve chamber 35. Wrenchapertures 36 are provided in the top of the valve seat member so that itmay be removed for repair or replacement by a new member having a largeror smaller conduit opening. The purpose of such replacement will be madeapparent in subsequent paragraphs.

Lateral apertures 37 through the wall of the body 23 interconnect theupper valve chamber 35 and the conduit 14. Thus gas from the main valvechamber 28 may join with the well fluids in the internal conduit 14 whenthe conduit 34 is open.

I prefer to provide a joint in that portion of tubular body 23 whichdefines the upper valve chamber 35 in order to allow access to the valveseat member 32. This is accomplished in the exemplary embodiment of Fig.2 by means of mating screw threads 38. Similar interbody joints whichare designed to facilitate disassembly and repair are provided atintermediate points 39 and 40. The plug 41 which closes the bottom ofbody 23 also is attached by screw threads 42.

Referring particularly to Fig. 2, a valve closure member 43 is designedto operate against valve seat member 32 to open and close the conduit 34extending therethrough. The closure member has a collar 44 which definesthe bottom of valve chamber 28, and an upwardly extending crown 45 whichcloses conduit 34. The collar has an internal recess 46 at the bottomwhich mates with the upper end of push rod 47. Thus the closure member43 is slidable on the push rod within the limits marked by the contactof the crown 45 with valve seat member 32 when the valve is closed, andthe contact of the top of the internal recess 46 with the upper end ofthe push rod 47 when the valve is open. In the embodiment of Fig. 2, thecollar is provided with an external resilient member 48 which provides aseal against the internal wall of the main valve chamber 28.

The lower end of push rod 47 is attached to the spring seat and stopmember 49 threadedly secured to rod 47. Compression spring 50 actsbetween the collar 44 and the spring seat member 49 to bias the valveclosure member 43 toward an upward or closed position.

Attached to and extending downwardly from the spring .seat member 49 isthe extension rod 51, the lower end of which is attached to the bellows52. The bellows is secured to the plug 41 in the bottom of the tubularbody 23 by appropriate means such as a transverse pin 53 acting betweenmating recesses in the plug. By filling to an appropriate pressure withgas or liquid, the bellows is adapted to provide an upward force on theextension rod 51 and, through member 49 and spring 50, on closure member43.

An annular guide bearing and stop 54 is formed Within that portion oftubular body 23 which surrounds exten sion rod 51. This member is inclose embracing relationship with the extension rod and is provided withan upper .conical seat '55 into which the lower portion of spring 4 seatmember 49 is adapted to fit. This serves the purpose of limiting thetravel of extension rod 51 and prevents damage to the bellows from anoverload in a downward direction on the valve closure member. A packingseal 56 is provided in the stop member 54 to prevent leakage of gaspressure from chamber 28 into the lower portion of the unit where thebellows is housed. This seal is a precautionary measure and supplementsthe seal 48 about collar 44.

The operation of the combined spring system represented by the coilspring 50 and the bellows 52 is a feature of my invention. When thevalve is closed, a portion of the closing force is provided by the coilspring and an approximately equal portion by the bellows. As the valveopens, the valve closure member moves downward on the push rod 47 as thecoil spring absorbs its proportionate share of the increased load andthe push rod 47, spring seat 49 and extension rod 51 all move downwardas the bellows absorbs its share. As the valve opening force increases,the limit of travel of the closure member on the push rod is soonreached at which time the coil spring is precluded from absorbing anyadditional load. Soon thereafter the spring seat bears against the seatmember 55 of the internal stop member 54, and the entire spring systemis bottomed out.

The combination of springs guards against a complete valve unit failurein the event of rupture of the bellows or fatigue of the coil spring.Either of the two spring members alone will provide a certain amount ofclosing force which even though less than that normally provided by bothwill suflice to close the valve and prevent expenditure of gas withoutproductive eflect. Furthermore, the use of the bellows provides arelatively constant spring which is not subject to the variations withextended use which characterizes a mechanical spring. Therefore suchvariation will have a relatively smaller efiect on a system whichincludes a constant unvarying spring member such as the bellows.

I prefer to employ a bellows which has a relatively large springconstant or modulus of elasticity, that is, a large force is required toproduce a small increment of movement, and a mechanical spring which hasa small spring constant or modulus of elasticity. With such arrangementof parts, the operating stroke of push rod 47 and extension rod 51 willbe very small and the extending movement of the spring necessary toeffect closure will decrease but a small amount of the total forcerepresented by the compressed spring. This tends to insure substantialopening of the valve upon slight increase in the pressure of gasadmitted through port 26 and/ or in the hydrostatic head above thevalve. This, in turn, avoids wire drawing eifect and excessive erosionat the valve.

My valve operates in the following manner. The entire unit is positionedinside the tubing 3 with the aperture 22 located between the upper andlower sealing rings 16 and 19. The gas under pressure in annular space 7enters the sealed chamber 21 through the port 22. It moves through thecheck valves 29 into the main valve chamber 28 where it is barred fromthe upper valve chamber 35 by the valve closure member 43 acting againstthe main valve seat member 32. In the embodiment shown in Fig. 2, theseal 48 about collar 44 confines the gas within the main valve chamber28 and the gas pressure acts downwardly against the collar of the valveclosure member, tending to open the valve conduit 34. The force exertedby this pressure is resisted by the spring system represented bycompression spring 50 and. the bellows 52. V

Oil or other fluids from the well will be free to pass through theapertures 15 in the lower portion 11 of the unit and move upwardlythrough the conduit 14 into the upper tubing through the upper end 18.This fluid will rise to the height in the well dictated by the internalpressure therein. As it moves through the conduit 14,it is free to enterthe upper valve chamber 35 through lateral apertures 37. The static headresulting from the weight of the fluid accumulated above the valve inthe tubing will be applied to the portion of the crown section 45 ofvalve closure member 43 which closes the conduit 34. The resulting forcewill add to the force created by the gas pressure in the main valvechamber 28 tending to move the valve closure member 43' downwardly.Thus, proper design of the springs in the system and the cross sectionalarea of the conduit 34 coupled with reasonably accurate control of thegas pressure will result in a valve unit which will open only when thereis a substantial column of liquids above it. Opening of the valve willallow gas to flow upwardly through the conduit 34 and out of theapertures 37, thereby lifting the well fluids upwardly through thetubing 3 to the top of the well. As soon as the weight of a sufficientportion of the column of liquid has been removed from the crown section45=by discharge from the top of the well to reduce the static head to apredetermined point, the spring system will again close the valve bymoving the valve closure member 43 upwardly.

Proper control of the above-mentioned design features will result in avalve which can be adjusted to meet the demands of various installationsand in each case function to release gas only when there is fluid to bemoved, thus materially saving in the amount of gas expended. Valve seatmember 32. can be readily replaced by a member having a larger orsmaller conduit 34 to meet varying installation requirements.

The embodiment illustrated in Fig. 2 is not responsive solely to theweight of the fluid above the unit in the tubing, for the gas pressurealso is utilized to provide additional opening force. This obviouslynecessitates control of the gas pressure in order to design the unit toopen in response to an exact. predetermined amount of fluid above theValve. In certain installations it may be undesirable or troublesome tocontrol the gas pressure closely, in which case certain structuralchanges will eliminate the effect of the gas pressure on the time ofvalve opening and result in a unit which is responsive solely to thepresence of fluid above it in the tubing.

These changes involve eliminating the seal 48 about the collar 44 andproviding lower apertures through the walls of tubular body 23- belowthe stopmember 54. Thus the gas pressure does not tend to move the valveclosure member 43', as it is free to fill the space under the collar 44and equalize itself. The only opening pressure exerted on the valve willbe the weight of the fluid acting on the crown section 45'.

In such case no effort is made to maintain the bellows 52 in a chamberof constant pressure. Instead, the mentioned lower apertures through thebody 23 allow the fluid in the conduit 14 to enter and surround thebellows. Obviously the upward force exerted by the bellows at any givenmoment would be a function of the pressure the bellows and the pressuresurrounding the bellows. Therefore, as the weight of the fluid in thetubing above the unit increases, the net force exerted by the bellows onthe valve decreases, and the unit may be designed so that a given amountof static head of fluid reduces the force exerted by the bellows to apoint where it, combined with the upward force of the coil spring, isequal to the downward force exerted by the same head on the crownsection 45 through conduit 34. Any additional head of fluid will openthe valve, and it will remain open until the static head has beenreduced to a point where the force of the spring system will overcome itto close the valve.

In the suggested modified unit, the seal 56 would prevent the fluidpressure surrounding the bellows from entering the upper part of thehousing 23. In all other respects, the operation of the modified valvewould be identical to that previously described.

The modified unit would posses certain advantages over the exemplaryunit. It is apparent that in the primary embodiment, the seals 48 and 56will be subject to leakage after a prolonged period of use. To preventsuch leakage from varying the design opening force required, it would benecessary to remove the valve at intervals and relieve any pressuressurrounding bellows 52 which had resulted from such leakage. In themodified device, no such internal pressures can build up, and the unitwould maintain design characteristics for a longer period of time.

For purposes of illustration, particular embodiments of the inventionhave been shown and described according to the best presentunderstanding thereof. However, it will be apparent to those skilled inthe art that many changes may be made in the construction andarrangement of the parts thereof without departing from the true spiritand purposes of the invention. Accordingly, it is desired to protect byLetters Patent all forms of the invention falling within the scope ofthe following claims.

The invention having been described, what I claim is:

1. A gas control valve comprising an elongated hollow valve bodyapertured adjacent one end thereof, a gas supply port communicating withthe interior of said valve body intermediate the ends thereof, a valveseat in said valve body between said port and said apertured end of saidbody, a push rod, a valve element sildably carried on said push rod andcooperable with said seat, a resilient, charged bellows operativelyconnected to said push rod and reacting against said valve body, toyieldingly urge said valve element toward said seat, an annular guideembracing said push rod between said port and said bellows, a stopmember fixed on said push rod and engageable with said guide in responseto predetermined yielding of said bellows, and a spring inten-posedbetween said valve element and said stop member to yieldingly urge saidvalve element into closing contact with said seat,

2. A gas control valve comprising an elongated hollow valve body havinga closed end and an apertured end, a gas supply port communicating withthe interior of said valve body intermediate the ends thereof, anannular valve seat in said valve body between said conduit and saidapertured end, a valve closure member slidable within said valve bodybetween said port and said closed end, said valve closure member havinga crown section extending therefrom adapted to engage said valve seat, aresilient seal between said valve closure member and said valve body, apush rod slidably engaging said valve closure member, stop meanslimiting the sliding movement of said valve closure member on said pushrod, a bellows operatively connected to said push rod and reactingagainst said valve body adjacent said closed end, a filling of acompressible medium under pressure in said bellows, said compressiblemedium extending said bellows to yieldingly urge said valve closuremember toward said valve seat, an annular guide bearing embracing saidpush rod between said conduit and said bellows, a sealing ring betweensaid guide bearing and said push rod, a stop member fixed on said pushrod, said stop member engaging said guide bearing in response to apredetermined yielding of said bellows, and a spring interposed betweensaid valve closure member and said stop member to yieldingly urge saidvalve closure member into closing contact with said valve seat.

3. A gas control valve comprising an elongated hollow valve body havinga closed end and an apertured end, a gas supply port communicating withthe interior of said valve body intermediate the ends thereof, anannular valve seat secured in said valve body between said conduit andsaidapertured end, a valve closure member within said valve bodyadjacent said valve seat, a push rod slidably engaging said valveclosure member, stop means limiting the sliding movement of said valveclosure member on said push rod, a bellows operatively connected at oneend to said push rod and fixed at its 7 other end to said valve bodyadjacent said closed end; a filling of compressible medium underpressure in said bellows, said compressible medium extending saidbellows to yieldingly urge said valve closure member toward said valveseat, an annular guide bearing embracing said push rod between saidconduit and said bellows, a sealing ring between said guide bearing andsaid push rod, apertures through said valve body between said guidebearing and said closed end, a stop member fixed on said push rod, saidstop member engaging said guide bearing in response to a predeterminedyielding of said bellows, and a spring interposed between said valve clo8 sure member and said stop'meniber to yieldingly urge said valveclosure member into closing contact with said valve seat.

References Cited in the file of this patent UNITED STATES PATENTS2,070,659 Higham Feb. 16, 1937 2,179,226 Bryan Nov. 7, 1939 2,217,305Bryan n Oct. 8, 1940 2,248,354 Jaworowsk-i July 8, 1941 2,465,060Oarlisle et a1. Mar. 22, 1949 2,668,553 7 Howard et a1. Feb. 9, 1954

